Influenza type A virus infection of suckling mice pre-exposed to insecticide carrier.

Suckling CD-1 outbred mice exposed topically to insecticide carrier (IC), a mixture of emulsifiers and solvent, were rendered less sensitive to infection with lethal doses of influenza type A/PR8/34 (H0N1) virus than untreated and mock-treated control mice. Decreased sensitivity to influenza type A/PR8/34 virus infection was evidenced by a significant increase in the mean percent survival of the mice. In addition, a 10- to 100-fold reduction in the 50% lethal titer of the stock virus was observed in IC-treated mice relative to untreated mice. Decreased sensitivity was virus dose related and occurred within a dose range of 2 to 8 X LD50. No decrease in mortality rate was observed as a function of exposure to IC.